The benefits of drinking water on an empty stomach are based on emerging or tangentially related scientific research. The benefits of drinking water on an empty stomach include positive effects for flushing toxins from the body, increasing energy and immunity, reducing weight and increasing metabolism, and preventing headaches and kidney stones. It aids in the cleansing of bowels and improves hair and skin health. Anecdotally, many people have reported feeling better after inculcating the habit of drinking water on an empty stomach, especially in the morning when the body is dehydrated.
Studies have generally not been conducted on the specific benefits of drinking water on an empty stomach, but there have been studies on the benefits of drinking water in the morning, before meals, and before exercise when the stomach is generally empty.
Drinking between 250ml and 500ml in the morning or before meals is commonly recommended, with no more than 1 liter per hour best because this is the maximum the kidneys can process. The benefits of staying hydrated throughout the day are also scientifically well established and show that drinking any type of potable water is important for maintaining the body’s homeostasis.
These are some of the key benefits of drinking water on an empty stomach.
- Drinking water on an empty stomach flushes toxins from the body.
- Drinking water on an empty stomach increases energy.
- Drinking water on an empty stomach cleanses your bowels.
- Drinking water on an empty stomach helps in reducing weight.
- Drinking water on an empty stomach speeds up your metabolism.
- Drinking water on an empty stomach promotes healthy hair.
- Drinking water on an empty stomach strengthens the immune system.
- Drinking water on an empty stomach prevents kidney stones.
- Drinking water on an empty stomach improves your skin.
- Drinking water on an empty stomach prevents headaches.
1. Drinking Water on an Empty Stomach Flushes Toxins from the Body
Medical experts say drinking water on an empty stomach flushes out toxins from the body. Drinking water when there is nothing present in your stomach allows the body to do its job more effectively. Doctors with Pinnacle Care Internal Medicine in Arizona say that “by drinking water immediately after waking up, your body is releasing toxins, which begins movement in your bowels. The water also purifies your colon, letting the organ absorb nutrients faster naturally.”
The body has its own processes to flush out toxins - the liver cleanses the system by changing the chemical nature of many toxins, and the kidneys filter them out of the blood via the urine. Some toxins can be easily removed but some require additional intervention. The presence of water improves the functions of the liver and kidneys to help dilute toxins in the bloodstream, making it easier to expel the waste material from the body.
This is why Dr. Steven Guest, a kidney specialist with Kaiser Permanente, says that “Your kidneys do an amazing job of cleansing and ridding your body of toxins as long as your intake of fluids is adequate”. The Arthritis Foundation agrees, saying that “if there’s a magical elixir you can drink, it’s water. Hydration is vital for flushing toxins out of your body, which can help fight inflammation”.
The diagram below shows some of the pathways by which toxins enter, and are removed from the body.
2. Drinking Water on an Empty Stomach Increases Energy
Drinking water is key to maintaining your energy levels. All the more so when you have an empty stomach after sleeping or other prolonged periods without water. Nathalie Pross, the Principal Clinical Scientist at Hoffmann-La Roche in Basel, Switzerland substantiated the claim that dehydration has detrimental effects on mood and performance in a 2014 study. She found that cognition tends to be impaired when you are dehydrated. This is especially the case for the elderly or children versus young, healthy adults who may have greater and more efficient resources.
Similarly, a 2019 study conducted on male college students in Cangzhou, China found that the subjects performed worse in cognitive tests and exhibited greater mood disturbance when dehydrated, and that these effects tended to decrease after they were allowed to rehydrate. Some notable results from this study are shown in the following plots.
Similar results were seen in a study entitled “Is Water-Only Fasting Safe?” by Ewa Ogłodek, MD, and Professor Wiesław Pilis from Jan Dlugosz University in Poland. The study looked at the efficacy of water-only fasting (WF) which is the absolute cessation of food consumption while consuming water only, meaning water is regularly being drunk on an empty stomach. The trial followed 12 middle-aged men who engaged in WF over a course of 8 days and noted a significant increase in the plasma concentration of β-HB. β-HB (β-hydroxybutyrate) supplies energy to the brain.
An increase in β-HB levels allows the body to be more energetic and helps to prevent or improve the symptoms of various age-associated diseases. The study noted that plasma osmolality was reported to be significantly decreased after 8 days of WF. Reduced plasma osmolality implies that chemicals are more diluted in the blood and give the body the energy to perform its job efficiently.
3. Drinking Water on an Empty Stomach Cleanses Your Bowels
“Water prevents constipation and helps our bowels expel waste” according to internal medicine specialist Dr. Jasvinder Anand of India’s Medanta Medicity Hospital. Water acts as a lubricant for the colon, and lack of it can trigger digestive ailments. Drinking water when the stomach is empty is one way to help prevent such ailments.
Dehydration is one of the most common causes of chronic constipation according to a 2006 paper that was medically reviewed by Minesh Khatri, MD. The digestive system needs water to keep food waste moving through it. If you don't have enough water in your body, the large intestine soaks up water from your food waste which causes you to have hard stools that are difficult to pass.
This was backed by a 2005 study on 898 children by A.Comas Vives et al at the Departamento Médico Solvay Pharma in Barcelona. According to the results, 73.4% of the children with intestinal constipation had a fluid intake of less than 4 glasses a day compared with only 47.1% without constipation.
4. Drinking Water on an Empty Stomach Helps in Reducing Weight
Science backs the claim that drinking water on an empty stomach helps in reducing weight. This is because it has a filling effect, as water takes up space in the stomach. This can cause you to limit food intake that would otherwise contribute to unwanted weight gain.
According to a 2008 study by Brenda M. Davy and her team from the Department of Human Nutrition, Foods and Exercise at Virginia Tech, consuming approximately 500 ml (2 cups) of water 30 minutes before a meal when the stomach is empty reduces meal intake by approximately 60 - 74 kcal in adults. The specialists observed a group of 24 overweight adults and concluded that adults who drank water on an empty stomach ate 13 percent less food than adults who didn’t drink fluids before eating. The following plot from the Virginia Tech study shows the results for all participants.
Similar results were seen in a 2016 study by Robert A Corney and his colleagues at the School of Sport, Exercise and Health Sciences at Loughborough University in the UK. Participants who drank two glasses of water immediately before a meal ate 22% less than those who didn't drink any water prior to eating.
The temperature of the water plays a significant role. There have been claims that drinking cold water on an empty stomach jump-starts your metabolism. Clive Brown and his team of researchers from the University of Fribourg in Switzerland conducted a study in 2006 that noted that drinking cold water at 37°F (3°C) caused a 5% increase in the number of calories burned.
This is supported by another study entitled Water Induced Thermogenesis by Michael Boschmann and his team of researchers at the Medical Faculty of the Charité of Humboldt-University, which found that drinking cool water had a greater effect on increasing metabolic energy expenditure than drinking water warmed to approximately body temperature. These results are displayed in the plot below.
Based on these studies, science points to the fact that drinking water, especially on an empty stomach, helps in reducing weight, and that this effect is greater if the water is cold.
5. Drinking Water on an Empty Stomach Speeds Up Your Metabolism
There is clear scientific evidence that indicates drinking water on empty stomach speeds up your metabolism. According to a 2003 study by Michael Boschmann et al. from the Medical Faculty of the Charité at Humboldt-University, drinking 500 ml of water increased metabolic rate by 30 percent. The study followed 14 adults (7 males and 7 females) and concluded that the increase occurred within 10 minutes and reached a maximum after 30-40 minutes. The study goes on to note that drinking 2 liters of water per day would augment energy expenditure by approximately 400 kJ. The graph below shows the increase in energy expenditure reported for each participant in this Boschmann et al. study after drinking water.
Drinking water appears to stimulate thermogenesis or heat production, according to a scientific study on water drinking habits entitled “Yes, Drinking More Water May Help You Lose Weight” published under the umbrella of Johns Hopkins University. The body has to expend energy to warm the fluid to body temperature, and the more energy expended by your body, the faster your metabolism (the process by which your body converts what you eat and drink into energy).
Health professionals back the claim that drinking water assists your metabolism. Alissa Rumsey, a registered dietitian with the Academy of Nutrition and Dietetics said drinking water regularly “does ensure that your metabolism is functioning optimally".
6. Drinking Water on an Empty Stomach Promotes Healthy Hair
While there is no evidence to show a correlation specifically between drinking water on an empty stomach and hair health, proper consumption of water, in general, does do so. According to the US National Research Council, water contains minerals like iron, zinc, copper, and calcium that are needed for maintaining hair health.
Copper can affect the pigmentation of your hair and its deficiency can cause hair abnormalities. Calcium keeps your hair healthy and shiny. A deficiency in iron or zinc can cause temporary hair loss whereas its supplementation can stimulate hair growth.
The quality of the water consumed affects hair quality according to a study by J. Lu and F. Yuan from The Arctic University of Norway. Drinking water is the primary source for the trace elements that hair needs to be healthy and hydration is essential for improved hair health regardless of the timing.
The USA's National Center for Biotechnology Information found local water provided up to 4.9% of the daily requirement of copper, up to 15% of the zinc, and up to 3.3% of the iron required by a 70kg adult.
7. Drinking Water on an Empty Stomach Strengthens the Immune System
Scientific research supports the claim that drinking water on an empty stomach strengthens the immune system by improving various body functions. In a study conducted by Gohar Sedaghat et al. at the Department of Nutrition of Iran’s Zahedan University, 40 patients with Type 2 Diabetes were given water on an empty stomach. At the end of 8 weeks, the subjects had lower BMI, waist circumference, and greater weight loss, as well as lower fasting blood sugar levels.
Additionally, drinking water on an empty stomach had caused a reduction in cholesterol levels (LDL-C), triglyceride, and copeptin. High triglyceride levels cause thickening of the artery wall and increase the chances of heart diseases where high levels of copeptin increase the risk of chronic kidney diseases. These charts summarize the results of the Sedaghat study.
In another 2020 study, Yumi Nakamura from Suntory Global Innovation Center in Kyoto Japan collaborated with colleagues from different research centers to undertake a randomized control trial involving 24 healthy Japanese men and 31 healthy Japanese women for 12 weeks. Subjects were required to drink 550 ml (2 cups) water on top of habitual fluid intake within 2 hours of waking up, and 550 ml water 2 hours before bedtime.
The study used urine, saliva, and blood as biomarkers and came to the conclusion that this pattern of water supplementation showed numerous health benefits that positively impact the body’s immunity. These include increased body temperature, reduced blood urea nitrogen, dilution of blood waste materials, and improved kidney function. Systolic blood pressure also decreased on average from 123.8 to 117.4.
According to a study entitled “Changes in the Blood Components Caused by Water Intake” by Hyun-Kyung Kim, Soo-Hwan Kim, Jae-Ki Ryu at the Gimcheon University in Korea, steady and sufficient water intake (which includes in the morning and other times where the stomach is empty) contributes to alleviating anemia by increasing hemoglobin.
Additionally, it may decrease the risk of cardiovascular disease by decreasing platelet activation and concentrations of high-sensitivity C-reactive protein (hs-CRP). CRP is used to assess the risk of cardiovascular disease. Furthermore, a steady intake of water may improve immune function by increasing the concentration of the components of immunity.
8. Drinking Water on an Empty Stomach Prevents Kidney Stones
Drinking water is essential for preventing kidney stones. The European Association of Urology’s guidelines suggest that daily fluid intake that achieves at least 2.5 liters of urine output per day can protect against kidney stones because chronic dehydration can result in kidney stones. Despite the well-known positive effects of high fluid intake, thus far there is only a small amount of research to date regarding the benefits of the specific timing of drinking water.
One possible piece of evidence comes from a study conducted by Gohar Sedaghat et al. at the Department of Nutrition of Iran’s Zahedan University. 40 patients with type 2 diabetes were given water on an empty stomach and at the end of 8 weeks, patients exhibited a decrease in copeptin levels. High copeptin levels are indicative of chronic kidney diseases.
This Youtube video was produced by the Mayo clinic to describe the causes of and ways to prevent kidney stones.
9. Drinking Water on an Empty Stomach Improves Your Skin
The skin is 70-75% water and drinking water is believed to improve skin quality regardless of when one drinks it. While there have not yet been studies done on whether the timing of drinking matters for skin health, Dr. Steven Deliduka, a board-certified dermatologist with Forefront Dermatology, says that “Without adequate water intake, skin appears duller. Proper hydration levels help the skin to become plump and improve its elasticity meaning it’s less likely to crack and have irritations and blemishes.”
A 2007 study in the International Journal of Cosmetic Science looked at the effects of long-term water intake on skin health. The study found that drinking 2.25 liters (9.5 cups) of water every day for four weeks had a significant impact on skin density and thickness.
The health benefits of drinking water in the morning and before meals already make it beneficial to drink at these times when the stomach is empty. So skin health is an added benefit even if there is not yet data showing if the timing has a specific added benefit.
10. Drinking Water on an Empty Stomach Prevents Headaches
Headaches are strongly linked to dehydration and drinking water can assist in preventing headaches.
Faezeh Khorsha et al. at the Department of Community Nutrition of Tehran University researched the association between dehydration and headaches by working with 256 women (18-45 years old) for 30 days. The results of her study showed that the severity of migraine disability, pain severity, headaches frequency, and duration of headaches were significantly lower in those who consumed more water.
Ayurvedic medicine also teaches that water helps with headaches. According to Dr. L.A Dongarwar who has over 35 years of experience in Ayurveda, dehydration is one of the major causes of headaches as the cells crave water for proper functioning. Drinking water, especially on an empty stomach, gives the cells their much-needed hydration, thereby preventing headaches.
There is no research on whether drinking when the stomach is empty has additional positive effects over any other time, but because drinking on an empty stomach in the morning and before meals is beneficial, headache prevention is a further bonus.
What Are Some Things to Know about Drinking Water on an Empty Stomach?
Some things to know about drinking water on an empty stomach are that pregnant women should not do it because regular food consumption is important, and that one should not drink to excess despite the hunger or thirst brought on by an empty stomach.
According to the Sickness & Vomiting in Pregnancy Information Leaflet by the UK’s National Health Service (NHS), pregnant women should eat often precisely to prevent the stomach from becoming empty and to prevent low blood sugar. They recommend regular meals and snacks, eating at least six times daily, even if nauseous or vomiting. Drinking non-caffeinated fluids consistently alongside eating is very important, with a recommended 1.5 to 2.5 liters per day. Food and fluids go together when pregnant, so drinking water on an empty stomach should not occur.
While an empty stomach may mean a higher appetite than normal, the kidneys can still only process about 0.8 to 1 liter per hour. And while drinking water may help reduce calorie intake to help lose weight, drinking too much water such that one is not hungry enough to eat a balanced meal with sufficient nutrients is not a good idea. Drinking a modest amount of water and then following it up with a healthy meal is best.
How Much Water Should You Drink on an Empty Stomach?
You should drink between 250 - 500 ml (1.5-3 cups) on an empty stomach. This suggestion is based on a study by Emily L Van Walleghen et al at the Department of Human Nutrition, Virginia whereby patients consumed 250-500ml water on an empty stomach to examine effects on eating patterns. In the absence of conclusive scientific consensus on the ideal water amount you should consume in a day, this may be considered a safe limit.
Dr. Parmeshwar Arora who is a senior consultant at Sir Gangaram Hospital in Delhi, India recommends drinking 250 ml (1.5 cups) of specifically warm water in the morning on an empty stomach. He also recommends drinking water slowly and keeping it in the mouth for 5-10 seconds before gulping it down.
Whatever amount is chosen, one should not drink more than 0.8 - 1 liter per hour on an empty stomach. A June 2013 study in the Annals of Pediatric Endocrinology and Metabolism states that this is the maximum amount a normal functioning kidney can process.
Humans experience stomach aches or nausea when drinking too much water on an empty stomach. According to an article entitled “Hyponatremia (Low Level of Sodium in the Blood)” by Dr. James L. Lewis of the Brookwood Baptist Health in Birmingham, Alabama, drinking too much water can lead to fluid overload and imbalance in the body. It upsets the sodium and electrolyte balance which may further lead to nausea, vomiting, cramps, and fatigue. If you experience nausea or vomiting after drinking water on an empty stomach, it may be because this balance has been upset. Cease drinking water and the symptoms should subside shortly.
When Is the Best Time to Drink Water on an Empty Stomach?
The best time to drink water on an empty stomach is in the morning, before a meal, and before exercise depending on the outcome expected.
The six to eight hours of recommended nightly sleep is a long period to go without any water consumption. Sarah Krieger, a registered dietitian nutritionist from Florida, states this is because “you don't drink while you're sleeping and you wake up already dehydrated. Having water can get you back up to your baseline”.
Dr. Maria Peña, an obesity medicine specialist at Mount Sinai Hospital in New York, says that drinking water in the morning is good for overall health. The body can become relatively dehydrated overnight, and "By hydrating more, you're getting rid of bad bacteria in your system, and it allows good bacteria in your gut to grow".
Melissa Mitri, RDN, owner of Melissa Mitri Nutrition LLC in Milford, Connecticut recommends drinking water before a meal. “Drinking a cup of water before a meal can help you feel more full and help prevent overeating.”
Excerpts also recommend drinking water before, during, and after exercise. A November 2019 study by Lewis J. James et al. of the National Centre for Sport and Exercise Medicine at Loughborough University in the UK shows that going into a race dehydrated even by a small amount can decrease performance. Mitri recommends drinking a cup of water about 30 minutes prior and then sipping during exercise.
This chart suggests how seven servings of water can be distributed throughout the day to maximize health benefits, based on current science.
What Type of Water Should You Drink on an Empty Stomach?
The type of water you should drink on an empty stomach is any type of potable water you most prefer. This includes tap water, spring water, mineral water, reverse osmosis water, artesian water, distilled water, reverse osmosis water, well water, mist water, rainwater, and all types of arctic water including iceberg water. “Potable” water is a keyword here as, depending on the specific source of the water, you may need to filter or boil it first to ensure it is safe.
Assuming the water is potable, while all types are beneficial, the healthiest types tend to be mineral waters because of the healthy compounds they deliver to the body. From a purity-from-pollution perspective, iceberg water tends to be among the most protected natural sources. Distilled and reverse osmosis water have had pollutants thoroughly removed through artificial processing, but they have also had healthy trace elements removed.
On average, whether water is delivered via tap or bottle is not the relevant issue from a safety or taste perspective, as was pointed out in a 2011 study by Zhihua Hu, et al. from Iowa State University citing scientific research showing little difference between tap and bottled water on those metrics.
You can add different flavors and ingredients for variety. Add the juice of half a lemon to a glass of lukewarm water, then add in a dash of cinnamon and 1 teaspoon honey. This drink will bring flavor to your water, keep you warm during the cold weather, and bring health benefits of honey and lemon. Adding fruits, ginger, or cucumber to the glass are other popular and healthy flavor options.
Is Drinking Lemon Water on an Empty Stomach Harmful?
Drinking lemon water on an empty stomach is not harmful, though there are some specific health circumstances such as acid reflux that may warrant moderation.
According to a study published at the US National Library of Medicine, one lemon has up to 31mg of Vitamin C, which can meet as much as 51% of the body's daily requirement of Vitamin C. Experts at the Edison Institute of Nutrition recommend drinking lemon water on an empty stomach. The best way, according to them, is to add half of a freshly squeezed lemon to 8 ounces of cool, warm, or hot water. Others recommend slightly lower or higher concentrations of lemon in water.
However, for those susceptible to heartburn, registered dietitian Lauren O’Connor reminds us that “Lemons are naturally acidic with a pH between 2 and 3. That is bad news for acid reflux sufferers because acidic foods trigger heartburn and can irritate an already inflamed throat (a symptom of Silent Reflux)”.
Note that this does not mean that lemons are bad for overall body health due to their acidic nature. The stomach is already a highly acidic environment to break down food no matter how alkaline. But if you have an inflamed throat, the lemon juice may cause irritation before it reaches the stomach.
The benefits of lemon water are not specifically tied to drinking it on an empty stomach. “If you enjoy the taste of lemon water over plain water, then this would be a good way of drinking more water,” says Vandana Sheth, RDN, CDE, spokesperson for the Academy of Nutrition and Dietetics.
What Is the Effect of Drinking Turmeric Water on an Empty Stomach?The effects of drinking turmeric water on an empty stomach include anti-inflammatory, antidiabetic, and antioxidant health benefits.
Turmeric has long been recognized for its medicinal properties as it is the major source of curcumin. According to a 2011 study by Susan J Hewlings et al. from the Department of Nutrition at Central Michigan University, curcumin has anti-inflammatory, antidiabetic, and antioxidant properties. It may also help in the management of exercise-induced inflammation and muscle soreness.
However, the body doesn’t absorb curcumin from turmeric very well and most studies that have investigated the effects of turmeric and curcumin have used high-dose supplements, not turmeric in water as a tea.
Indian nutritionist and author Munmun Ganeriwal recommends drinking turmeric tea for a number of benefits. "Turmeric is not only beneficial but also perfect for the colds that are common between changing seasons. It has its own distinctive flavor. It has proven to ease arthritis symptoms and helps in cancer prevention." She recommends adding a bit of black pepper powder to turmeric tea because components of pepper help in better absorption of curcumin.
You can add the following spices to make your turmeric tea taste better.